The invention belongs to the field of technologies applied to treating kitchen waste, and particularly discloses a synergistic fermentation system applied to treating kitchen waste. The synergistic fermentation system comprises a sludge collecting device, a first mixing device, a mixing stirring tank, a second mixing device, an aeration tank of a sewage plant, an SBR (sequencing batch reactor) nitrogen removal device, a second mixing assembly, a digestion pot and a kitchen waste pretreatment device. The first mixing device, the mixing stirring tank and the second mixing device are respectively connected with the sludge collecting device, the aeration tank of the sewage plant and the mixing stirring tank are respectively connected with the first mixing device, the SBR nitrogen removal device is connected with the aeration tank of the sewage plant, the second mixing assembly is connected with the SBR nitrogen removal device, the digestion pot is connected with the second mixing device, the mixing stirring tank is connected with the digestion pot, and the kitchen waste pretreatment device is connected with the mixing stirring tank. The synergistic fermentation system applied to treating the kitchen waste has the advantages that the synergistic fermentation system is reasonable in design and structure, the kitchen waste is directly combined with a municipal sewage treatment plant during operation, and accordingly resources can be efficiently reused; the kitchen waste can be treated in an environment-friendly manner, and secondary pollution can be prevented.